They are popular as they provide a simplified proof of the Uw value of windows.
For the Ψ values of facades however, it was necessary to perform detailed calculations for each individual case, until now. That is now finally comes to an end, at least for mullion-transom facades. In a research project by the "Warm Edge" working group, appropriate parameters have been defined. Just in time for the “Fensterbau Frontale”, the BF plans to issue the "Psi values for facades" data sheets. For each warm edge spacer system, there will be then a sheet available with representative Ψ values – naturally also for the Thermix® TX.N® plus spacer.
The representative facade psi values can be used to calculate the Ucw value as long as the specifications of ift guideline WA-22/1 are adhered. The use of these values is to be constituted as a standard in the new version of DIN EN ISO 12631. This will probably take place in autumn 2016.
All currently valid data sheets are also published on the BF website.